Jimena, just short of Category 5 status -- the top danger rating for a hurricane -- could rake the harsh desert region fringed with picturesque beaches and fishing villages as a major storm by this evening, forecasters said.

On Monday afternoon, workers at the Cabo San Lucas marina nailed sheets of plywood on storefront windows while fishermen secured their boats. Hotels and restaurants gathered up umbrellas, tables, chairs, and anything else that might be blown away.

At least 10,000 families will be evacuated from potential flood zones, said local Civil Protection Director Francisco Cota. He said 60 shelters would be set up.

Los Cabos Mayor Oscar Nunez said people in poorly constructed homes face "a huge potential risk" right now and may be forced to evacuate.

Brenda Munoz, who lost her home to a 2001 hurricane, was taking no chances.

"I remember when Hurricane Juliette hit with a lot of intensity. It flattened our home," Munoz said in the vacation town of Cabo San Lucas. This time, she said, "We're already prepared with food and everything so it won't catch us off guard."

As rain started falling Monday morning, Mitch Williams of Orange County, California, waited at the airport to fly home from his vacation.

"The hurricane can do a lot of damage if it hits at that strength," he said.

Williams said poorer residents who live in shacks are not well prepared.

"It will wipe them out," he said.

His advice for tourists was simple: "Get out."

But on Cabos' famous beaches, some tourists were doing just the opposite, jumping into the Pacific to play in the hurricane's big waves.

Although city officials shut down the port, lifeguard Roman Dominguez with the Cabo San Lucas Fire Department said there's no feasible way to close a beach.

"We struggle a lot with surfers," he said. "They're looking for waves."

Lifeguards perched in a tower looked on Monday as two women, one with her boogie board, another on a surf board, paddled into pounding surf under cloudy skies.

Clay Hurst, 52, a fencing contractor from Malibu, California, and Ben Saltzman, 28, an emergency medical technician from Pacific Palisades, California, emerged from a swim in the 10-to-12-foot (3-to-4-meter) waves and pounding surf.

"We are waiting anxiously, wanting to be right in the middle of it," said Hurst, who said he has never seen a hurricane as powerful as Jimena.

"We were advised to leave, but we want to be here," he said. "I've always wanted to be in one ... a real bad one."

But Cabos San Lucas fishing boat captain Eleazar Unzon, a 30-year veteran of these waters, was more cautious.

"This is causing a lot of fear and concern," said Unzon, 58, as he and helpers pulled the 33-foot (10-meter) fishing boat "Alejandra" onto a trailer. "We're getting the boat out of the water before it hits, so we can rest easy at home."

Unzon acknowledged that big storms do have some benefits -- he notes that they bring in the "big fish" coveted by sports fishermen such as marlin -- but said, "I'm not going to expose my livelihood."

Tim Donnelly, 57, a boat captain originally from Washington, D.C., sat dockside after tying down the 105-foot (32-meter), two-masted wooden schooner "Sunderland," saying he expected the 140-year-old wooden boat to ride out the storm.

"We've never been hit by a storm of this category," he said. "I'll be shocked if we don't have any problems."

Farther south, Jimena kicked up surf along Mexico's mainland western coast and generated strong winds that bent and uprooted trees in the resort town of Zihuatanejo. Authorities in other mainland towns were setting up shelters as a preventive measure.

By Monday afternoon, Jimena was a Category 4 storm with maximum sustained winds near 155 mph (250 kph) and was moving northwest near 10 mph (15 kph), the U.S. National Hurricane Center in Miami reported. It was centered about 305 miles (495 kilometers) south of Cabo San Lucas.

Hurricanes reach Category 5 at 156 mph (250 kph).

Farther out in the Pacific, Tropical Storm Kevin weakened to a tropical depression with top winds of 35 mph (55 kph). It was centered 845 miles (1,355 kilometers) west-southwest of the Baja peninsula's southern tip.